1. Field of the Invention
The present invention relates generally to detection, identification, and classification of metallic objects, and more particularly, to a system and method for using ferromagnetic loops to identify and classify vehicles.
2. Background of the Invention
A typical automatic toll collection system for a highway involves the use of a toll collection station or toll booth positioned between each lane of traffic. Vehicles driving on the highway must pass through a toll lane alongside the toll collection station.
The passage of vehicles by the toll collection stations is monitored with a combination of loop detectors, treadles, or other such devices capable of detecting passing vehicles. These devices provide vehicle classification information after the vehicle has passed a payment point. Although these devices can be used for audit purposes, they do not address the potential for error when an attendant makes a mistake, nor do they address the ability to properly classify all transactions.
In early toll collection systems, attendants were employed to manually collect fares from the operators of vehicles and to regulate the amount of tolls. Utilizing attendants to collect fares involves numerous problems including, but not limited to, the elements of human error, inefficiencies, traffic delays resulting from manually collected tolls, employment costs of toll attendants, and embezzlement or theft of collected toll revenues. As a result, devices have been developed to automatically operate toll collection systems without the need for toll attendants. In these systems, the toll fees paid can be based on a combination of the number of axles on a vehicle as well as a set price per vehicle.
However, known tolling systems designed to operate without a toll booth attendant intervention are typically based on several heterogeneous components that are not optimized to work together.
One example of a toll system that can collect tolls of different toll rates from different classes or categories of vehicles without user intervention is described in the '937 application. The '937 application discloses an intelligent vehicle identification system (IVIS) that includes one or more inductive loops. The inductive loops disclosed in the '937 application includes signature loops, wheel assembly loops, intelligent queue loops, wheel axle loops, gate loops, vehicle separation loops, and enforcement loops.
The '972 application discloses additional designs, configurations, installation, and other characteristics associated with the loops previously disclosed in the '937 application. In other words, a ferromagnetic loop in accordance with the teaching of the '972 application can be adapted to be utilized as one or more of the loops disclosed in the '937 application. Of course, the ferromagnetic loops of the '972 application have applications beyond those in the toll road context and those disclosed in the '937 application. For example, the ferromagnetic loops of the '937 application can be adapted to serve various purposes including traffic law enforcement, traffic surveys, traffic management, detection of concealed metallic objects, treasure hunting, and the like.
The present application provides additional description to the '972 application.